And speaking of anime, if you check out Episode 1 of the animated "Gunsmith Cats," there's a close-up of a license plate that reads "NCC-1701", the Enterprise's registration number. More anime/manga spoilers...
"Appleseed"--Manga, Book 3, Issue 1--In the lower left hand corner of page 3, I believe, you can see a cameo of Kurt Russell as Snake Plissken. He even gives his trademark statement, "Call Me Snake!"
"Appleseed"--Manga, Book 2, Issue 1) Hold the book up to the mirror and look at the councilmember's tunics. Several works in English can be read.
And speaking of words, a Japanese issue of "Dominion" had a large blurb (in English) right inside the artwork "Appleseed Book 3 is nudeful and actionful." This was later removed for the American translated version.
"Gunsmith Cats"--In several issues of the comic book, look at Rally's Mustang's license plate. It varies between "NCC 1701" and "THX-1138."
"Dominion" The first series, Issue 5 or 6--At one point, Buaku (the half-robot super criminal) is wearing a shirt that has a (reversed)map of the world.
More later as I find them!

One more! In an episode of "Gundam Wing" (I forget which), there is a shot of Wing-Zero's cockpit. In the lower left corner of the dash is the phrase "Intel Inside." So Gundams run on the Windows platform?

Actually, the label says Intel Outside. It's on the missile Heero is trying to shut off to prevent the New Edward's base from being blown up and annihilating everything in a 180 mile radius. Wing Zero hadn't been built at that point, it was in the early episodes.

In Gundam 08th MS Team, when they are activating the big mecha (can't remember what it's called) that deals major death, if you look behind the main-character's-love-interest's-brother (Can you tell I haven't seen this in a while?), you'll see that the lit-up panels showing which systems are activating show things like "Pentium MMX" and "DirectX SDK."

It's been a long time since I have seen this movie but either before or right after the beer can goes streaking by there is a Coca Cola can going by also. As for the Battletech vs. Robotech issue this was an obvious enough 'cameo' to be caught by the Robotech people who successfully sued Fasa to remove the mech similarity.